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How long does it take for a Blue Seas Systems ACR to kill your battery if left idle and connected?
I had been unable to use the boat for maybe a month and came back to a dead batttery.
No problem I think, I just installed a new deep cycle as part of a stereo upgrade...I'll just combine batteries....click....
So. Another question- if the cranking battery is just plain bad, going to "Combine" position just connects the dead battery to the otherwise good one and drags it down, right?
There may be a parasitic loss somewhere, could be the amp is not turning off properly with the turn-off wire...or the ACR.
Any thoughts?

Yeah, if you leave the ACR on the battery side of the power switch it can drain the batteries, but dead in a month sounds pretty fast - I'd think it would be more on the order of a year plus to drain from a full charge. There's an alternate wiring scheme that switches the ACR out when you turn the switches off - see the attached. I did this just a month ago and it seems to work well so far, but I'd also keep an eye out for other possible drains on the battery (bilge pump, etc.).

John

Thanks for the reply.
We just installed an ACR, second battery, the Blue Seas switch that came in the kit, a stereo upgrade with JL amp...
I have to do a little troubleshooting to see what still has power with the battery switch off, make sure its just the normal stuff.
And to see if there is any current draw in that mode as well. Hope it was just a bad battery...time will tell!

The self discharge of batteries with Lead-Antimony plates can be high - as much as 1% per day on an older battery.
A new AGM typically self-discharges at about 1-2% per month, while an old one may be as much as 2% per week.


https://www.solar-electric.com/learning ... y-faq.html

okielaker wrote: Sat Aug 29, 2020 12:17 am The self discharge of batteries with Lead-Antimony plates can be high - as much as 1% per day on an older battery.
A new AGM typically self-discharges at about 1-2% per month, while an old one may be as much as 2% per week.


https://www.solar-electric.com/learning ... y-faq.html

That's a pretty informative site!
Unfortunately I traded in the old battery when I bought the new one and won't be able to have it tested.
Thanks for the info.

Update- after dealing with dual dead batteries, my son and I did some electrical troubleshooting. It turned out the ACR standby current was about 10ma. We also found that the Mercathode unit draws about 60ma with the boat out of the water. Both will kill two batteries dead in about 6-7 weeks. My plan is to pull the batteries for long term storage (winterized) but possibly put both those circuits on switches for in-season use, when I might not get to use the boat due to work, vacation, etc...

Mike in SC wrote: Mon Dec 14, 2020 9:01 pm Update- after dealing with dual dead batteries, my son and I did some electrical troubleshooting. It turned out the ACR standby current was about 10ma. We also found that the Mercathode unit draws about 60ma with the boat out of the water. Both will kill two batteries dead in about 6-7 weeks. My plan is to pull the batteries for long term storage (winterized) but possibly put both those circuits on switches for in-season use, when I might not get to use the boat due to work, vacation, etc...

I have an onboard charger so I just leave it turned on. If you plan on leaving the boat without a charger, turn battery switch off and put a switch in the ground lead going to the ACR to turn it off. Likewise turn off Mercathode by pulling a fuse.

On my pontoon boat, I have my ACR wired like the diagram above but most boats don't have that type of switch.You can't do that with a 1/2/Both switch that most of us have on these boats.

The reality of a 10mA drain is that it will consume a little over 7AH in a month. That's actually probably less than the battery's self discharge rate for a flooded lead acid battery.